You can feel your stomach churn your cum around inside you. You start thinking more and more about canine se and how wonderful it would feel to have another canine cock up your ass. You are so consumed by this that you don’t notice how late it is getting in the day. When you finally snap out of you trance, you first notice that your very, very horny and that you've shot cum all over your chest, fore legs, and the floor. You become very disappoint that you have missed out and eagerly start licking up as much up off the floor and yourself that you can. You just as your finishing up you hear a creaking sound from behind you turn to look not having finished cleaning it all off your chest yet. What you see makes you horny again. You see another rottweiler like yourself, who is also apparently horny and sniffing your ass. He trots over and you look up into he big brown eyes and think to yourself "omg is he hot". He bends head down and finish cleaning your cum of your chest. Cock comes to attention. He's finish you stand and immediately offer him your tight virgin ass. He moves behind you and starts slowly lubing you up, sticking tung in ass far he can cleaning you out. Waves of pleasure rack your body as your are moments away from climaxing panting with pleasure. Then he puts out he long an finishes lubing your out most self. Your disappointed by this hoping that he would have kept his tung in longer. Now done lubing you he throws him self up on your and rams you with his cock. He thrusts you as hard and as fast as he can. You racked by pleasure the feel of his cock in your ass is the most wonderful feeling you have ever felt in your life. You feel him and yourself coming to climax you position your open mouth in font of your cock and hope to catch as much of you cum as you can in it. Moments later you both climax and you mouth, face, and chest get covering with cum and your new mates seed fills you awaiting ass. He waits a few mins. more inside of you waiting for his knot to loosen a the while you enough ever second of it while lapping up as much of your cum as you can. He loosens and pulls out. You greatly saddened by this, but You notice now that his cock is out of you just how wonderful it feels you have his seed in you as it moves around inside you pleasuring you more. He comes around and help you lap up what is left of your cum on you face and chest. You getting hard again as his seed pulses stimulating you more and more. Your mate puts your cock in his and sucking in rhythm with is his pulsing cum. You climax again your ball letting loose another load into his mouth. He gulps is it down and keeps sucking you a soon climaxing again shooting out another load for him which he also gulps down. The seed has stopped pulsing now and he stops sucking. You its now your turn to mount him, but your wrong he moves be hind you and licking your hole again and he probes his lung deeper into your hole again lapping out all of his seed you whimper wanting to taste for you self but he commands you to remain still as he laps it up finishing up and pulling out his lung just before you climax again. You feel something happening to your stimulated cock and balls. You look to see what going on to find that your cock is getting longer and thicker, and your balls are going more massive. Your mate stands and waits seeming to know what is going on. After about a minute or two go by your modification is complete and your cock has gained about 1" in length and width and your balls are twice as big as they were.